The top ends of beverage (e.g. beer and soda) cans are formed in high volumes using presses such as those disclosed in U.S. Pat. No. 4,568,230, issued to Omar L. Brown on Feb. 4, 1986, and U.S. Pat. No. 4,723,882, issued to Wissman et al. on Feb. 9, 1988. In general, these presses include a main press having tooling for forming can ends and a continuous, can end transfer belt extending therethrough to carry can end blanks from a supply of blanks, support the can ends during stamping, and transfer the can ends away from the stamping station. The transfer belts are typically fabricated from a material such as stainless steel and include carrier openings. (U.S. Pat. No. 4,946,028, issued to Eichmann et al. on Aug. 7, 1990, and U.S. Pat. No. 5,158,410, issued to George D. Hunt on Oct. 27, 1992, disclose such transfer belts.)
The transfer belts are typically supported between two drums. One of the drums is an idler drum and the other drum is a drive drum including drive teeth. The drive drum is rotated by an appropriate drive train and motor, and the teeth of the drum cooperate with carrier openings in the transfer belt to index the belt and associated can ends through the press.
One reason for using metal transfer belts is to maintain tight tolerances while stamping can ends. Furthermore, to maintain tight tolerances, it is also important that the drive teeth and carrier openings are closely matched so that accurate control of the drive motor will result in precise indexing of the transfer belt. The importance of accuracy resulted in the use of drive teeth and carrier openings rather than just the friction force between the transfer belts and the drive drum. However, as a result of operation, the frictional force between the drive drums and drive belts acts to wear the carrier openings and/or the drive teeth. This wear is a result of the drive teeth exerting high forces against the carrier openings to slide the belt against the friction force when the teeth and openings become misaligned during operation. As a result of wear of the teeth and/or openings, the accuracy of belt indexing decreases until the belt must be discarded. In the case of many can end presses belts are discarded on a weekly basis.
In view of the problems discussed above, it would be desirable to provide and improved transfer belt drive mechanism which reduces the wear between the drive teeth and the associated carrier openings of the belt.